Auto merge of #4276 - alexcrichton:revert2, r=alexcrichton
authorbors <bors@rust-lang.org>
Thu, 13 Jul 2017 04:19:23 +0000 (04:19 +0000)
committerbors <bors@rust-lang.org>
Thu, 13 Jul 2017 04:19:23 +0000 (04:19 +0000)
[beta] Don't set MAKEFLAGS for build scripts

Closes #4156
Closes rust-lang/rust#42635


Trivial merge